Ground effect craft with divergent channel

ABSTRACT

This invention relates to an advanced marine ground effect design concept achieving aerodynamic lift with thrust contributing forces by fluid flow through a divergent channel in the bottom of the craft. The invention is illustrated as applied to a motor boat hull having catamaran sections on both sides of the divergent channel. Velocity head of air is converted into pressure head in the channel to develop lift and forward thrust.

United States Patent [191 Wukowitz [451 Apr. 10, 1973 1 GROUND EFFECT CRAFT WITH DIVERGENT CHANNEL [76] Inventor: Edward Wukowitz, 29

Avenue, Congers, NY. 10920 [22] Filed: Apr. 7, 1971 [21] App]. No: 131,858

Wells [52] US. Cl. ..ll4/67 A, 114/665 R [51 Int. Cl. ..B63b 1/38 [58] Field of Search ..1 14/67 A, 66.5 R

[56] I References Cited UNITED STATES PATENTS Wukowitz ..1 14/67 A Baldwin ..1 14/67 A 1,875,344 9/1932 Kloen ..1 14/665 R Primary ExaminerMilton Buchler Assistant Examiner-Stuart M. Goldstein Attorney-Sandoe, Hopgood & Calimafde [5 7 ABSTRACT This invention relates to an advanced marine ground effect design concept achieving aerodynamic lift with thrust contributing forces by fluid flow through a divergent channel in the bottom of the craft. The invention is illustrated as applied to a motor boat hull having catamaran sections on both sides of the divergent channel. Velocity head of air is converted into pressure head in the channel to develop lift and forward thrust.

14 Claims, 11 Drawing Figures PATENTEDA 1 W73 3. 726.246

INVENTOR v BYW AW ATTORNEYS.

GROUND EFFECT CRAFT WITH DIVERGENT CHANNEL BACKGROUND AND SUMMARY OF THE INVENTION One object of this invention is to provide a craft with exceptional performance capabilities in a seaworthy hull over a wide range of operating conditions and mission fulfillments showing great versatility and adaptability.

This invention also substantially reduces power requirements by its high efficiency and effectiveness craft providing lift. For practical purposes a portion ofthe divergent channel can be designed into the vehicle. While that section of the vehicle forms a portion of the divergent channel, the remaining portion or side is formed by the continuous earth or water surface passing beneath. With the top portion of the divergent channel (incorporated in the hull) sliding over a land or water surface, a moving divergent channel is made and pressure induced therein. This pressure acts to:

l. raise the moving vehicle 2. contribute a thrust component by acting on an expanding surface 3. depress the surface underneath, if not solid(water;

mud) An opening isprovided forward for intake. In land applications a simple arrangement is'possible allowing for adequate sliding or rolling means over an underlying surface or tracks, with adequate (sufficient) sealing means between surfaces for greater efficiency.

While on sea, the opening is at a fixed forward location provided with means for keeping waves out of the passage and at the same time smoothing the sea surface as it slides (flows) under the hull. This is accomplished in the illustrated embodiment of the invention by the use of a Vee section forward and a step arrangement leading into a channel between catamaran keel sections. The trailing edge of the step and side wall keel surfaces provide adequate sealing service with water contact. In sea applications the water surface provides a more ideal surface for sliding and sealing, but considerations for buoyancy and stability become more important, and are incorporated into the inventions hull design.

A Vee section forward is preferred as it provides an easy entry in rough sea with good shock resistance. The bow opening also effectively dissipates portions of waves as they pass harmlessly through the air passage and the air provides buoyancy and a cushion effect that adds to the comfort of persons riding in the craft.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

BRIEF DESCRIPTION OF DRAWING In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIG. 1 is a side elevation of a boat hull made in accordance with this invention, the hull being shown out of the water;

FIGS. 2 through 7 are sectional views taken on the lines 2-2 through 77, respectively, of FIGS. 1 and 8;

FIG. 8 is a bottom plan view of the boat hull shown in FIG. 1, on a reduced scale;

FIG. 9 is a front view of the boat hull shown in FIGS. 1 and 8;

FIG. 10 is a stern view of the boat hull shown in FIGS. 1, 8 and 9; and

FIG. 11 is a diagrammatic view showing the way in which the center keel seals the low part of the air passage provided by the tunnel.

DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 shows a boat hull 20 which has a forward deck 22, a cockpit 23 and an afterdeck 24. At the sides of the hull there is a gunwale 26 and the hull has top sides 28 extending from the gunwale on each side of the hull down to a chine 30.

The hull 20 has an outer bottom 32 and has an inner bottom 34 (FIG. 3). There is an air passage side wall 36 extending from the center of the outer bottom 32 up to the inner bottom 34. A similar air passage side wall 36 on the starboard side of the hull forms an air passage which is bounded on top by the portion of the inner bottom 34 that extends from the top of the side wall 36 to the top of the side wall 36'. This air passage,- designated by the reference character 40, is divided down its center by a keel element 42.

The keel element 42 is a structural element for strengthening the hull and it is connected at its upper end with the inner bottom 34 and at its lower end with the center of the outer bottom 32.

As the side walls 36, 36 extend forward they contact with the outer bottom 32 and at this region of contact the side walls 36 and 36' terminate as shown by the forward end view of these walls 36 and 36' in FIG. 2. The outer bottom 32 has openings 44 through it forward of the terminations of the side walls 36 and 36'. These openings 44 extend to the forward end of the hull and serve as air scoops for bringing air into the passage 40 44 or in conjunction with them, the hull may have openings or air scoops in the deck 22 near its forward end and these air scoops may be provided with any deflectors or ventilating cowls as desired. Although spray and waves can also enter the openings 44 on occasions, this does no harm to the boat since the air passage supplied by the openings '44 does not at any place lead into the interior of the hull above the inner bottom 34.

The outer bottom 32 is continuous across the hull until it reaches a region designated in FIG. 8 by the reference character 46. From the region 46, the lower ends of the outer bottom 32 and the air passage side wall 36 on the port side and 36' on the starboard side separate from the keel element 42 as shown in FIG. 4. Thus the juncture of the portions of the outer hull 32 that meet the side walls 36 and 36' form in effect a step 48 (FIG. 8) at which the air from the air passage 40 comes in contact with the water under the hull. The side walls 36 and 36 still form the side walls of an air passage which is designated in FIG. 4 by the reference character 40; this air passage 40 being a continuation of the air passage 40 and differing from the air passage 40 in that the water under the air passage forms the lower side of the air passage. The inner bottom 34 still forms the top of the air passage 40'.

At regions indicated by the reference characters 50 in FIG. 8 the side walls 36 and 36 reach a vertical position, as shown best in FIG. 5, and as these side walls 36 and 36 extend further aft, they converge toward their upper ends as shown in FIGS. 6 and 7. From the points 50, in FIG. 8, the portions of the outer bottom 32 on opposite sides of the hull and the side walls 36 and 36' of the air passage form what are well-defined catamaran sections of the hull. The air passage between the side walls 36 and 36', after the passage has only a water bottom, is a channel in the bottom of the hull di- The rolling position shown in FIG. 11 leaves one side of the air passage 40' open to the atmosphere through the space 54 which opens up between the bottom of the starboard catamaran section as that section lifts clear of the water 56. This would release pressure from the entire air passage or tunnel 40' if it were not for the keel element 42 but this keel element maintains a seal for the lower side of the air passage 40 as long as the keel element 42 can dip into the water 56. Thus air pressure in the lower or port side of the air passage 40' is maintained and this increases the righting effort of the hull 20.

It is a feature of the invention that the air passage 40 and its continuation 40 diverge as it extends aft. This divergence is brought about partly by the increase in the spacing between the side walls 36 and 36 and also by a rise in the level of the inner bottom 34, as will be evident from FIG. 1. Air which enters the openings 44 or scoops at the forward end of the air passage 40 flows into the passage at high speed relative to the boat hull when the boat hull is travelling through the water. As the air moves aft in the passage 40-40' and the cross section of the passage increases, the velocity of the air decreases and the velocity head of the air is converted into pressure head which appears as pressure against the water under the channel and forming the bottom of the air passage comprising the air passage 40. This pressure lifts the hull and reduces the wetted surface and the displacement.

If greater pressure under the hull is desired, air can be supplied to the forward portion 40 of the air passage by a blower. When a power driven blower is used, the scoop openings 44 are closed by shutters or other means (not shown). By also providing temporary closing of the air passage at its transverse exit the craft cam be given lower capability.

When the boat is travelling at high speed, the passage of air through the air passage 4040 in contact with the inner bottom 34 exerts aerodynamic lift.

Pressure of the air against the diverging side walls of the air passage 4040 has a forward component which adds additional thrust for moving the hull through the water. It has been observed that the air movement in the tunnel along the boundary layers which contact with the keel element 42 on the side walls 36 and 36 involve eddy currents where the air and the water in immediate contact with the air has a forward movement. This may be merely friction drag, or it may be the result of aerodynamic effects caused by the divergence of the air passage.

The catamaran sections indicated generally by the reference characters 60 in FIGS. 6 and 7 have a Vee bottom which provides keels of the hull for a portion of the length of the hull; and toward the aft end of these catamaran sections the bottom of the Vee is cut away on an angle as illustrated by the bottom section 62 in FIGS. 1 and 7. This bottom section 62, on each of the catamaran sections 60 extends up to the chine line 30 and provides for side venting of the air passage between the catamaran sections. This side venting, which is optional, has the advantage of permitting escape of pressure from the air passage some distance ahead of the transom 66 so that the lift at the transom is somewhat reduced to keep the transom from rising excessively and causing the bow to dip, and for reducing pressure to avoid porpoising effects.

The necessity for the venting provided by the cut away bottom section 62 depends upon the design of the forward portion of the hull and the slope forward of the outer bottom 32 which fomis the outer sides of the catamaran sections toward the stem or transom and it can be used to offset lift which is excessive at the transom and which causes the hull to pop out of the water on occasions when under way.

The apparent curve of the lines 68 in FIG. 8, which represent the lines where the side walls 36 and 36 of the catamaran sections meet the inner bottom 34, are to a certain extent optical illusions. They appear to curve because of the fact that the side walls 36 and 36 are converging at this part of the hull and the inner bottom 34 is rising (see FIG. 1). This combination causes the upper ends of the side walls 36 and 36' to meet the inner bottom 34 at locations which are higher where the side walls 36 and 36' have converged further, thus producing the curved effect. Actually the side walls 36 and 36 are plane surfaces at this region of the hull and so is the inner bottom 34; or if the inner bottom has any curve it is in a direction about a transverse plane and not a vertical one as might be indicated by the appearance of the lines at 68 in FIG. 8.

The hull is propelled through the water by inboardoutboard drives 70 each of which has an engine 72 located in the catamaran section to which the inboardoutboard drive is connected. Conventional air screws can be used instead of inboard-outboard drives, if desired, or jet propulsion can be used, either water or gas.

The preferred embodiment of the invention has been illustrated and described but changes and modifications can be made and some features of the invention can be used in different combinations without departing from the invention as defined in the claims.

WHAT IS CLAIMED IS:

1. A ground effect craft including a body having a forward portion with a double bottom comprising an inner bottom and an outer bottom with space between them providing an air passage, means for supply air to the forward end of the air passage, at least a portion of the transverse width of the outer bottom terminating at the rearward end of the forward portion, a rearward portion of the body having a channeled bottom which forms a continuation of the air passage beyond the termination of the outer bottom, the sides of the channel extending down to the lower limit of the outlet end of the portion of the air passage enclosed by the double bottom, and characterized by the channel portion of the air passage increasing in cross-section as it extends toward the rearward end of the body of the craft, said channel portion having an outlet at the rearward end of the body.

2. The ground effect craft described in claim 1 characterized by the air passage diverging to greater cross-section in both the space between the inner and outer bottoms and along the channel, the divergence along the channel resulting at least in part from divergence of the side walls of the channel.

3. The ground effect craft described in claim 1 characterized by the increase in cross-section of the channel as it extends rearwardly, resulting at least in part from a rising level of thebottom of the body of the craft with respect to the lower limits of the sides of the channel.

4. The ground effect craft described in claim 1 characterized by the body being a motor boat hull, the sides of the channel being catamaran sections of the hull, and the air passage rearward of the outer bottom termination being closed at its bottom by the water under the channel when the boat hull is afloat.

5. The ground effect craft described in claim 4 characterized by a center keel element bisecting the channel lengthwise and extending downward, into the water when the craft is afloat, for sealing one-half of the width of the channel when the craft lists far enough to raise the other side of the channel clear of the water 6. The ground effect craft described in claim 5 characterized by the keel extending down as far as the sides of the channel when the craft is floating in a transversely level condition, and the craft having Vee bottom catamaran sections forming the sides of the channel and providing other keel elements.

7. The ground effect craft described in claim 5 characterized by the center keel element extending forward into the portion of the air passage enclosed by the double bottom and providing structural connection between the inner and outer bottoms of the double bottom.

8. The ground effect craft described in claim 4 characterized by side walls on the part of the air passage enclosed in the double bottom extending beyond that part of the air passage and forming the sides of the channel.

9. The ground effect craft described in claim 8 characterized by said side walls throughout most of the length of the channel converging toward one another as they extend upward, the angle of convergence decreasing toward the forward end of the channel, and said side walls being of warped contour and reaching a arallel relation to one another at one station engthwise of the craft, and said side walls forward of .tact with one another along an inner surface of the outer bottom and forming with the inner bottom a part of the air passage in the space enclosed by the double bottom, said part of the air passage being of generally triangular cross-section.

11. The ground effect craft described in claim 4 characterized by one of the side walls having a portion that provides an open space at the side of the channel near the stern of the craft but forward of the aft end of the craft for venting some air from the side of the channel before the rest of the air reaches the exit of the channel.

12. The ground effect craft described in claim 4 characterized by the catamaran sections of the craft being substantially parallel to one another for a part of the length of the craft near the stern thereof.

13. The ground effect craft described in claim 4 characterized by the longitudinal center lines of the catamaran sections as they extend aft diverging from one another for most of the length of the craft.

14. The ground effect craft described in claim 4 characterized by the hull having caramaran sections forming opposite sides of the channel, each of the catamaran sections being of Vee cross-section with each side of each catamaran section diverging from the other side as it extends upward and with the outside surfaces of the sides of each catamaran section at acute angles to a horizontal plane along the parts of the catamaran sections that are aft of the forward portion of the hull, the outboard sides of the catamaran sections having their outside surfaces at an acute angle to a horizontal plane along the full length of the catamaran sections, but the inboard sides of the catamaran sections having their outside surfaces warped and coming to vertical orientation at one station of the hull and then making an obtuse angle with a horizontal plane at locations forward of said station, the inboard side of each catamaran section approaching closer to the outboard side as the sides extend forward and meeting and connecting with the outboard side at a forward end of said inboard side of each catamaran section, the outboard sides of the catamaran sections extending forward beyond the ends of the inboard sides and meeting one another at the stem of the hull and forming the outer bottom of the hull and having openings therethrough above the water line of the hull, which openings comprise air inlets and the means for supplying air to the forward end of the air passage. 

1. A ground effect craft including a body having a forward portion with a double bottom comprising an inner bottom and an outer bottom with space between them providing an air passage, means for supply air to the forward end of the air passage, at least a portion of the transverse width of the outer bottom terminating at the rearward end of the forward portion, a rearward portion of the body having a channeled bottom which forms a continuation of the air passage beyond the termination of the outer bottom, the sides of the channel extending down to the lower limit of the outlet end of the portion of the air passage enclosed by the double bottom, and characterized by the channel portion of the air passage increasing in cross-section as it extends toward the rearward end of the body of the craft, said channel portion having an outlet at the rearward end of the body.
 2. The ground effect craft described in claim 1 characterized by the air passage diverging to greater cross-section in both the space between the inner and outer bottoms and along the channel, the divergence along the channel resulting at least in part from divergence of the side walls of the channel.
 3. The ground effect craft described in claim 1 characterized by the increase in cross-section of the channel as it extends rearwardly, resulting at least in part from a rising level of the bottom of the body of the craft with respect to the lower limits of the sides of the channel.
 4. The ground effect craft described in claim 1 characterized by the body being a motor boat hull, the sides of the channel being catamaran sections of the hull, and the air passage rearward of the outer bottom termination being closed at its bottom by the water under the channel when the boat hull is afloat.
 5. The ground effect craft described in claim 4 characterized by a center keel element bisecting the channel lengthwise and extenDing downward, into the water when the craft is afloat, for sealing one-half of the width of the channel when the craft lists far enough to raise the other side of the channel clear of the water
 6. The ground effect craft described in claim 5 characterized by the keel extending down as far as the sides of the channel when the craft is floating in a transversely level condition, and the craft having Vee bottom catamaran sections forming the sides of the channel and providing other keel elements.
 7. The ground effect craft described in claim 5 characterized by the center keel element extending forward into the portion of the air passage enclosed by the double bottom and providing structural connection between the inner and outer bottoms of the double bottom.
 8. The ground effect craft described in claim 4 characterized by side walls on the part of the air passage enclosed in the double bottom extending beyond that part of the air passage and forming the sides of the channel.
 9. The ground effect craft described in claim 8 characterized by said side walls throughout most of the length of the channel converging toward one another as they extend upward, the angle of convergence decreasing toward the forward end of the channel, and said side walls being of warped contour and reaching a parallel relation to one another at one station lengthwise of the craft, and said side walls forward of that station diverging from one another as they extend upward.
 10. The ground effect craft described in claim 9 characterized by the lower ends of said side walls along the portions thereof that diverge from one another as they extend upward approaching closer together at their lower ends as they extend forward until they contact with one another along an inner surface of the outer bottom and forming with the inner bottom a part of the air passage in the space enclosed by the double bottom, said part of the air passage being of generally triangular cross-section.
 11. The ground effect craft described in claim 4 characterized by one of the side walls having a portion that provides an open space at the side of the channel near the stern of the craft but forward of the aft end of the craft for venting some air from the side of the channel before the rest of the air reaches the exit of the channel.
 12. The ground effect craft described in claim 4 characterized by the catamaran sections of the craft being substantially parallel to one another for a part of the length of the craft near the stern thereof.
 13. The ground effect craft described in claim 4 characterized by the longitudinal center lines of the catamaran sections as they extend aft diverging from one another for most of the length of the craft.
 14. The ground effect craft described in claim 4 characterized by the hull having caramaran sections forming opposite sides of the channel, each of the catamaran sections being of Vee cross-section with each side of each catamaran section diverging from the other side as it extends upward and with the outside surfaces of the sides of each catamaran section at acute angles to a horizontal plane along the parts of the catamaran sections that are aft of the forward portion of the hull, the outboard sides of the catamaran sections having their outside surfaces at an acute angle to a horizontal plane along the full length of the catamaran sections, but the inboard sides of the catamaran sections having their outside surfaces warped and coming to vertical orientation at one station of the hull and then making an obtuse angle with a horizontal plane at locations forward of said station, the inboard side of each catamaran section approaching closer to the outboard side as the sides extend forward and meeting and connecting with the outboard side at a forward end of said inboard side of each catamaran section, the outboard sides of the catamaran sections extending forward beyond the ends of the inboard sides and meeting one another at the stem of the hull and forming the outer botTom of the hull and having openings therethrough above the water line of the hull, which openings comprise air inlets and the means for supplying air to the forward end of the air passage. 